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Passing planes and other whoosh sounds

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Re: Passing planes and other whoosh sounds

#51

Post by singleshot_ »

shmeeed wrote: post #7

I'm just armchair musing here, and I'm definitely no expert on sound waves, but I wonder if they considered the fact that most airliners have more than one engine. Could the effect also be the superposition of multiple engine sounds? Those have a fixed spatial distance, too, and the effect would (I suppose) change with the lateral angle to the listener during the fly-by. This theory should be pretty easy to falsify,…

Planes also have flaps, slats, and landing gear, which can have a huge effect on the sound heard on the ground.

Re: Passing planes and other whoosh sounds

#52

Post by LargoLasskhyfv »

oe wrote: post #15
roygbiv2 wrote: post #12

We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effect mixed with the valley we live in but I'm always very curious when it does happen. They make their usual sound but then there's a second sound that arrives, a lot higher pitched. Sounds like they've struck it in reverse or something (they haven't they're jus…

I think it’s some engine type that makes the sound at some specific speed / throttle setting. But I can’t remember the specifics. Some planes passing us make the sound, most don’t.

Could also be FOPPs, or both combined! (Fuel Overpressure Protection) https://aviation.stackexchange.com/questions/23701/what-caus...

Some do it at certain airspeeds, others don't. Depends on their shape, and can be mitigated/eliminated, which is sometimes done, other times none.

Re: Passing planes and other whoosh sounds

#53

Post by cf100clunk »

stouset wrote: post #50
cf100clunk wrote: post #48

Earlier quoted context omitted.

Neutrinos, cosmic rays, and extraterrestrial subatomic particle streams are not considered RF, right?

If we're going out of our way to eliminate things that cause zero perceptual experience I don't see why you would exclude them.

Those requirements were not specified, so were not designed or built. If you can increase the budget, we can write-up a proposal to wrangle some sufficiently-dense proto-neutron stars.

Re: Passing planes and other whoosh sounds

#54

Post by junon »

meindnoch wrote: post #26
junon wrote: post #20

Pretty sure this is also why, when you stand at the right spot in a techno concert, the music starts to sound like a jet engine. We also have this in game development, where if two sound effect emitters play the same effect at the same time with just a bit of offset, phase, whatever, they sound like that.

If the offset is fixed, the effect is called a comb filter. If the offset is changing, the effect is called flanging. The name stems from recording engineers rubbing their fingers against the flange of a reel-to-reel recorder's tape reel, to brake it slightly, which adds increasing delay to the sound.

Huh so a flange is just a combing effect that shifts around? I'd never considered this. Also neat fact about flanges, didn't know that either. Thanks!

Re: Passing planes and other whoosh sounds

#55

Post by roygbiv2 »

ano-ther wrote: post #14
roygbiv2 wrote: post #12

We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effect mixed with the valley we live in but I'm always very curious when it does happen. They make their usual sound but then there's a second sound that arrives, a lot higher pitched. Sounds like they've struck it in reverse or something (they haven't they're jus…

Very interesting question. I thought that was when they extend their flaps so the wings become a bit wider for the slower flight and that creates some resonance.

Mmm could be. I need more data. Eg is it when landing on one runway or are they going to the other one, cloud layers etc.

Re: Passing planes and other whoosh sounds

#57

Post by AStonesThrow »

junon wrote: post #20

Pretty sure this is also why, when you stand at the right spot in a techno concert, the music starts to sound like a jet engine. We also have this in game development, where if two sound effect emitters play the same effect at the same time with just a bit of offset, phase, whatever, they sound like that.

In the 1960s through 1980s, producers of audio recordings were striving to achieve something which they called “Wall of Sound”, which I suppose was influenced by producers like Phil Spector’s releases with the Beatles. It is a dense, all-encompassing sound with the drums, bass, guitars, keyboards and sometimes vocals too having equity in the mix, and not too much separation from left to right but a spacious “soundstage” effect, and just a solid onslaught of music for the duration of the track.

Well, there was a legend about a certain band fronted by Stan Ridgway. In the late 1970s they were in the studio and the producers were tweaking knobs and sliders to approach the desired sound. And one of them asked whether it was a “Wall of Sound” yet, but another replied, “it sounds more like a Wall of Voodoo!”

https://en.wikipedia.org/wiki/Wall_of_Voodoo#Formation

Re: Passing planes and other whoosh sounds

#58

Post by jononor »

meindnoch wrote: post #40
cf100clunk wrote: post #39

Earlier quoted context omitted.

If you are handy to an R&D lab that has a combo Faraday Cage/anechoic chamber you can have a nice experience free of RF and audio noise and stimulus. Even better if it is dimly lit in near-infrared. Even better-better if it has a tank of warm water with lots of epsom salts, although I've never been in a lab that had such a thing as a requirement.

I'm skeptical of shielding yourself from RF noise having any detectable effect. Unless you have amalgam tooth fillings, that anecdotally can act as a crude diode, and demodulate strong enough AM signals.

RF anechoic chambers are, as a side effect of their construction, pretty low echo also when it comes to audible frequencies. I have spent a bit of time in one (EMC testing a product), and it was the quietest room I have been in by far.

Re: Passing planes and other whoosh sounds

#59

Post by dredmorbius »

arnarbi wrote: post #43

There was a pretty good video on this a couple of years ago: https://www.youtube.com/watch?v=QFv3QPNU6hw

TL;DW: The apparent tone shift is a result of interference from a bounce-path echo (from the ground) to the listener of the white noise emission of the aircraft, rather than expected doppler effect. This can be experimentally verified several ways, e.g., changing the bounce length (by moving closer or further from the ground) or by monitoring similar noises of known origin near an acoustically-reflective surface.

Re: Passing planes and other whoosh sounds

#60

Post by kpil »

roygbiv2 wrote: post #12

We have planes pass overhead at about 6000ft. When the conditions are right they'll make a completely different sound, I've always assumed it's the Doppler effect mixed with the valley we live in but I'm always very curious when it does happen. They make their usual sound but then there's a second sound that arrives, a lot higher pitched. Sounds like they've struck it in reverse or something (they haven't they're jus…

Extending flaps for approach makes a rather distinct woosh going from high to low pitch over a few seconds.
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